Related Clues:

• Stain
• Smudge
• It may be found in a proof
• Delete, with 'out'
• Splotch
• Proof goof
• Rorschach stain
• Error
• Dab
• Erratum
• Printing mistake
• Inky mess
• Soak up
• Rorschach test image
• ThiS, e.g.